The formation and evolution of dwarf galaxies in diverse cosmological environments

不同宇宙环境中矮星系的形成和演化

• 批准号: 2457517
• 金额: --
• 依托单位: Liverpool John Moores University
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2020
• 资助国家: 英国
• 起止时间: 2020 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2457517
• 关键词: formation; evolution; dwarf; galaxies; diverse

The lambda Cold Dark Matter (lambda CDM) cosmological model is the currently-preferred paradigm for explaining the large-scale structure of the cosmos. However, reconciling its small-scale predictions with observations of dwarf galaxies poses outstanding challenges (e.g. Bullock and Boylan-Kolchin, 2017). Classified by stellar masses below ~10^9Msol and dark matter halo masses below ~10^11 Msol, dwarf galaxies represent some of the oldest and most dark matter dominated systems in the cosmos, and their shallow gravitational potential wells make them particularly sensitive to a diverse range of internal and external astrophysical processes. They are therefore sensitive probes for testing the predictions of galaxy formation models *and* the prevailing cosmogony.Deep optical surveys have recently fostered the discovery of many more, ever-fainter, dwarf galaxies, and it is expected that the forthcoming Vera Rubin Observatory will dramatically accelerate the rate of new discoveries. Existing observations have already revealed remarkable diversity among the fundamental properties of the faintest dwarfs, including their kinematics, size, gas content and star formation histories. To date, reproducing these properties in numerical models has proven challenging. Moreover, the very formation mechanism of the faintest dwarfs remains uncertain, and poses a major question at the forefront of contemporary astrophysics. The leading hypothesis is, at present, that they are relics of the early universe, which formed at high redshift and were quenched during the epoch of reionization (Simon, 2019).This PhD thesis aims to scrutinise this hypothesis using cosmological zoom-in simulations run with the next-generation, state-of-the-art galaxy formation model: COLIBRE. COLIBRE ncorporates a more sophisticated treatment of interstellar gas physics than the current state-ofthe-art, in addition to superior dynamics achieved by using equal mass baryon and dark matter particles. It is therefore ideally suited to examination of dwarf galaxies. We will study dwarf galaxies in a diverse range of environments by creating a series of simulations complementary to the flagship COLIBRE run: these will be "zoomed" spherical regions, selected from the (300Mpc)^3 EAGLE-XL parent volume. Each will have a radius of 5-10Mpc (dictated by computational limitations), and with various mean overdensities but devoid of massive haloes (M200 > 10^12 Msol). The latter condition mitigates computational cost and allows us to increase the resolution to 10^4Msol per baryonic particle whilst still simulating a large volume.

lambda冷暗物质（lambda CDM）宇宙学模型是目前解释宇宙大尺度结构的首选范例。然而，将其小尺度预测与矮星系的观测相协调构成了突出的挑战（例如布洛克和Boylan-Kolchin，2017）。矮星系的恒星质量低于10^9 Msol，暗物质晕质量低于10^11 Msol，它们代表了宇宙中最古老、暗物质占主导地位的系统，它们的浅引力势威尔斯使它们对内部和外部的各种天体物理过程特别敏感。因此，它们是检验星系形成模型 * 和 * 流行的宇宙起源学的预测的灵敏探针。最近，深层光学巡天促进了对更多的、越来越微弱的矮星系的发现，预计即将建成的维拉鲁宾天文台将大大加快新发现的速度。现有的观测已经揭示了最暗矮星的基本性质之间的显着差异，包括它们的运动学，大小，气体含量和星星形成历史。到目前为止，在数值模型中再现这些属性已被证明具有挑战性。此外，最微弱的矮星的形成机制仍然不确定，并构成了当代天体物理学前沿的一个重大问题。目前，主要的假设是，它们是早期宇宙的遗迹，在高红移时形成，并在再电离时期被淬灭（Simon，2019）。这篇博士论文旨在使用宇宙学放大模拟来仔细研究这一假设，该模拟使用下一代最先进的星系形成模型：COLIBRE。COLIBRE采用了比目前最先进的星际气体物理学更复杂的处理方法，除了通过使用等质量重子和暗物质粒子实现的上级动力学之外。因此，它非常适合检查矮星系。我们将通过创建一系列与旗舰COLIBRE运行互补的模拟来研究各种环境中的矮星系：这些模拟将是从（300 Mpc）^3 EAGLE-XL母体积中选择的“放大”球形区域。每个星系的半径都在5- 10 Mpc之间（由计算限制决定），有各种各样的平均超密度，但没有大质量的晕（M200 > 10^12 Msol）。后一个条件降低了计算成本，并允许我们将分辨率提高到每个重子粒子10^4Msol，同时仍然模拟大体积。